The present invention relates to a support means system, which comprises a drive pulley and a belt-like support means and serves for moving a load, as well as an elevator installation with such a support means system. Fields of use for such a support means system are, for example: supporting and drive systems for cars of passenger and goods elevators, for mining conveying equipment, for elevatoring devices of high-bay warehouse vehicles, for elevatoring devices of stacking vehicles, for elevatoring equipment in conveying systems of production lines and packaging lines, for brush elevatoring equipment in washing installations, for elevatoring equipment in fitness training apparatus, etc. The support means system is also suitable for, for example, use as a conveyor belt of belt conveyors or belt excavators.
The support means system according to the present invention is described in the following on the basis of use thereof as a support means system of an elevator installation.
Elevator installations usually comprise an elevator car and a counterweight, which are movable in an elevator shaft or along free-standing guide devices. For generating the movement, the elevator installation comprises a drive unit with at least one drive element in the form of a drive pulley, wherein the drive pulley supports the elevator car and the counterweight by way of at least one flexible supporting and/or drive means and transmits the requisite drive forces thereto. Necessary additional deflections of the supporting and drive means are usually realized by deflecting elements in the form of deflecting pulleys.
The supporting and/or drive means is termed simply support means in the following and where the description refers not only to drive pulleys, but also to deflecting pulleys these are called support means pulleys. However, it is not essential for the drive means pulleys to have an actual pulley shape; these can also have the shape of a shaft or axle.
An elevator installation is shown in European patent document EP 1 555 234 A1 in which wedge-ribbed belts are used in support means for the elevator car. These belts comprise a belt body of flat-belt kind, which is produced from resilient material (rubber, elastomer) and which has on the running surface thereof facing the drive pulley several ribs extending in a belt longitudinal direction. These ribs co-operate with corresponding grooves in the periphery of drive or deflecting pulleys in order on the one hand to guide the wedge-ribbed belts on the support means pulleys and on the other hand to increase the traction capability between the drive pulley and the support means. The ribs and grooves have triangular or trapezium-shaped, i.e. wedge-shaped, cross-sections. Tensile carriers consisting of metallic or non-metallic strands are embedded in the belt bodies of the wedge-ribbed belts to be oriented in belt longitudinal direction and impart the requisite tensile strength and longitudinal stiffness to the support means.
The elevator installation disclosed in EP 1 555 234 A1, in which wedge-ribbed belts are used as support means, has certain disadvantages. One of the disadvantages is that the wedge-ribbed belt does not attain an optimum drive capability and the resulting drive capability does not remain constant in the course of the operating life. This problem results from the fact that a substantial part, which is not, however, constant in the course of the operating time, of the radial forces transmitted by the wedge-ribbed belt to the drive pulley is transmitted not by way of the inclined flanks of the ribs and grooves, but in the region of the rib crests and groove bases in an approximately radial direction because the rib crests rest in the corresponding groove bases. This part of the radial forces, which is not clearly determinable and not constant, is not converted, or is converted only to a small extent, by wedge action between the inclined flanks into increased normal forces between belt and drive pulley. Moreover, in the case of the support means described in the cited state of the art the problem exists that dirt and belt abraded material are collected and compacted in the grooves of the support means pulleys and also in the grooves of the support means. This on the one hand has a consequence that at least in places the direct contact between the support means pulley and the belt is prevented, which strongly reduces the traction capability between a belt pulley and the support means. On the other hand, a thick contamination hardened in the groove base prejudices lateral guidance of the support means on the support means pulleys and in the extreme case leads to the support means being laterally displaced relative to the support means pulley or even the running surface leaving the support means pulley. Not only the loss of drive capability, but also the lateral displacement or the jumping-off of the support means from the support means pulley can lead to serious operational disturbances of the elevator installation.
A further disadvantage of the support means disclosed in EP 1 555 234 A1 is that faultless co-operation between the wedge-shaped ribs and grooves of the support means and the corresponding ribs and grooves of the support means pulley is disturbed when the support means is used in conjunction with support means pulleys having an extremely small outer diameter. The reason for that is that as a consequence of the high compressive stresses resulting as a consequence of support means curvature in the region of the rib crests of the support means the ribs deform in such a manner that they are displaced out of their correct position in the wedge-shaped grooves of the support means pulley. If the support means pulley is a drive pulley a reduction in traction capability can result therefrom.